The present invention relates generally to electronic power supply devices and more particularly to an improved high average power magnetic modulator for metal vapor lasers.
It has become recognized that pulsed power supplies employing magnetic compression circuits are appropriate for use with high power pulsed lasers. Even though such power supplies are more expensive and more complex than some other known modulator types, the high reliability of magnetic switch modulators is deemed to be necessary for critical applications, and the higher the output power required the greater is the improvement in the reliability of such modulators as compared to more conventional electronic pulsed power supply devices using thyratrons, or the like, as the ultimate switching circuit elements. An example of a particular such magnetic compression laser driving circuit, particularly adapted for high efficiency operation, is found in U.S. Pat. No. 5,177,754 issued to Ball et al..
Due to the fact that high average power magnetic compression laser driving circuits produce a great deal of heat, and further due to the fact that they produce very high voltages, they have been designed to be operated immersed in a liquid dielectric fluid, which fluid acts both to improve voltage hold off and as a coolant. However, known fluorocarbon dielectric fluids which have been used for this purpose present environmental problems, and are becoming unavailable for that reason. Therefore, it is desirable to produce a magnetic compression laser driver circuit which can operate without the use of such fluids. However, efforts to produce a device which can provide the necessary power for those applications which require very high power, without the use of fluorocarbon dielectric and coolant fluid and with the requisite reliability, have been less than completely successful. Primary switching stages using thyratron switches have proven to be less than optimal due the inherently finite life of such switches. Solid state devices have been tried but these generally lack the ability to deliver the instantaneous power and/or rate of change of current necessary for the task.
To the inventors' knowledge, no previous magnetic compression laser driving circuits which can produce the very high power output required by high average power lasers (greater than 30 kW) and which function without the use of fluorocarbon coolants or dielectrics have been known in the prior art. All previous such devices have either required the use of fluorocarbons or else have produced insufficient voltage and/or power output for some applications.